<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>score</title>
</head>
<body>
<script>
    function Grade(score) {
        if (score >= 90) {
            console.log('A');
        } else if (score >= 80) {
            console.log('B');
        } else if (score >= 70) {
            console.log('C');
        } else if (score >= 0) {
            console.log('D');
        } else {
            console.log('分数无效');
        }
    }
    Grade(95);
    Grade(85);
    Grade(75);
    Grade(65);
    Grade(-5);

</script>

</body>
</html>
